As the process for polymerizing polymerizable unsaturated compounds, such as olefins and styrenes, to produce homopolymers and copolymers, processes using catalysts which comprise a transition metal compound, an ionic compound or an organic aluminoxy compound which can form an ionic complex compound by reaction with the transition metal compound, and optionally, a metal compound containing alkyl group have heretofore been known.
In the above homogeneous polymerization catalysts, the organic aluminoxy compound used as a component is a reaction product of an organoaluminum compound and water and forms a coordination polymerization catalyst by reaction with the transition metal compound. However, the known polymerization catalysts prepared by using an organic aluminoxy compound have a drawback in that polymers cannot be produced with stability and high activity because the properties of the catalyst show large dispersion.